1. Field of the Invention
The present invention relates to a magnetic recording medium, and more specifically, to a magnetic recording medium having good running durability and stability for use in high-density recording, and to a magnetic signal reproduction method and magnetic signal reproduction system employing the magnetic recording medium.
2. Discussion of the Background
Magnetic recording media are employed to record a variety of information such as audio, video, and text. In recent years, the demand for higher density recording has increased with the increased quantity of information being recorded. There is need for a magnetic recording medium affording good electromagnetic characteristics with few defects in the magnetic layer surface causing signal loss.
Since magnetic recording media are employed to repeatedly read and write information, running durability with repeated use (repeat running durability) is required. To achieve good repeat running durability, a backcoat layer having surface protrusions is provided on the opposite surface of the nonmagnetic support from the surface on which the magnetic layer is provided to reduce the frictional coefficient. However, when a magnetic recording medium is stored in a rolled state during manufacturing or when a magnetic tape is stored wound on a reel hub following production of the final product, the protrusions on the surface of the backcoat layer transfer to the surface of the magnetic layer, forming minute indentations in what is known as “reverse transfer.” As a result, not only do electromagnetic characteristics end up deteriorating, but there are drawbacks in that minute dropout increases, increasing the error rate. On the other hand, when the surface of the backcoat layer is smoothed to eliminate problems such as “reverse transfer,” the shape of the tape when wound following running becomes chaotic, a winding defect known as “radial” occurs, and tape deformation such as creasing of tape edges sometimes occurs.
By contrast, to achieve both a reduction in reverse transfer and improve the appearance in the winding state, Japanese Unexamined Patent Publication (KOKAI) 2005-18821 or English language family member US 2004/0265643 A1 proposes a medium in which the distribution of protrusions on the surface of the backcoat layer as measured by an atomic force microscope (AFM) is specified. The contents of these applications are expressly incorporated herein by reference in their entirety. However, to deal with the higher density recording of recent years, an even greater reduction in dropout is needed.